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authorFrederic Weisbecker <fweisbec@gmail.com>2008-11-11 07:03:45 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-11 10:29:11 +0100
commitcaf4b323b02a16c92fba449952ac6515ddc76d7a (patch)
tree6fc234d00faca192248344996a168afb253e5f40 /arch/x86/kernel/entry_32.S
parentd844222a54c33a960755b44b934cd1b01b05dceb (diff)
tracing, x86: add low level support for ftrace return tracing
Impact: add infrastructure for function-return tracing Add low level support for ftrace return tracing. This plug-in stores return addresses on the thread_info structure of the current task. The index of the current return address is initialized when the task is the first one (init) and when a process forks (the child). It is not needed when a task does a sys_execve because after this syscall, it still needs to return on the kernel functions it called. Note that the code of return_to_handler has been suggested by Steven Rostedt as almost all of the ideas of improvements in this V3. For purpose of security, arch/x86/kernel/process_32.c is not traced because __switch_to() changes the current task during its execution. That could cause inconsistency in the stored return address of this function even if I didn't have any crash after testing with tracing on this function enabled. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/entry_32.S')
-rw-r--r--arch/x86/kernel/entry_32.S33
1 files changed, 33 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 9134de814c9..9a0ac85946d 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1188,6 +1188,10 @@ ENTRY(mcount)
cmpl $ftrace_stub, ftrace_trace_function
jnz trace
+#ifdef CONFIG_FUNCTION_RET_TRACER
+ cmpl $ftrace_stub, ftrace_function_return
+ jnz trace_return
+#endif
.globl ftrace_stub
ftrace_stub:
ret
@@ -1206,8 +1210,37 @@ trace:
popl %edx
popl %ecx
popl %eax
+ jmp ftrace_stub
+#ifdef CONFIG_FUNCTION_RET_TRACER
+trace_return:
+ pushl %eax
+ pushl %ecx
+ pushl %edx
+ movl 0xc(%esp), %eax
+ pushl %eax
+ lea 0x4(%ebp), %eax
+ pushl %eax
+ call prepare_ftrace_return
+ addl $8, %esp
+ popl %edx
+ popl %ecx
+ popl %eax
jmp ftrace_stub
+
+.globl return_to_handler
+return_to_handler:
+ pushl $0
+ pushl %eax
+ pushl %ecx
+ pushl %edx
+ call ftrace_return_to_handler
+ movl %eax, 0xc(%esp)
+ popl %edx
+ popl %ecx
+ popl %eax
+ ret
+#endif /* CONFIG_FUNCTION_RET_TRACER */
END(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_TRACER */